That's correct, take some of the slack up on the adjuster under the van. I park one side on the kerb and run the other up on my levelling ramps. Even at the age of 72 I can shimmy under the van OK like that, done it hundreds of times during the past 14 years converting five vans!. A big sheet of cardboard makes sliding under even easier!
No point in being a DIY camper builder if you can't get under your van easily.